1. Field of the Invention
The present invention relates to an overhead type air conditioning unit for a vehicle, and especially relates to the art to reduce the overall thickness of the air conditioning unit, for improving the mounting capability of the unit in the vehicle.
This application is based on Japanese Patent Application No. Hei 11-101715, the content of which is incorporated herein by reference.
2. Description of the Related Art
Conventionally, in a vehicle such as a limousine, an air conditioning unit can be provided which is exclusively used for rear seats, which consists of a second line or second and third lines of the seats of the vehicle, is mounted. This air conditioning unit is mainly mounted in the ceiling of the passenger component as shown in FIGS. 14 and 15, and is generally referred to as an overhead type air conditioning unit.
A conventional overhead type air conditioning unit is briefly explained as follows with FIGS. 14 to 22.
FIGS. 14 and 15 show an example of the overhead type air conditioning unit (hereafter, called "a rear air conditioning unit ") which is provided for a sedan type passenger car. Reference number 1 in these figures indicates the rear air conditioning unit. In this unit, compressed coolant which is compressed by a compressor and has high temperature and high pressure, is cooled by a condenser and is supplied to the rear air conditioning unit 1 and a front air conditioning unit (not shown).
FIG. 15 shows the rear air conditioning unit 1 mounted at the ceiling of the passenger component and is shown from the rear side of the passenger component. The rear air conditioning unit 1 is fixed on body 3 by brackets 2 at both ends. In practice, for preventing the exposure of the mounting members such as the brackets 2, a treatment such as covering these members with an appropriate covering member (not shown) is performed.
Furthermore, in this rear air conditioning unit 1, as shown in FIGS. 16 and 17, improvements such as installing the unit between two reinforcement members 5 which are located at the passenger-component side of roof panel 4 and extend along the width direction, are performed to restrict the projection of the unit into the passenger component as much as possible. This improvement is carried out to secure as much headroom as possible under restricted conditions, to provide a comfortable space in the vehicle.
In succession, the structure of the conventional rear air conditioning unit 1 is briefly explained as follows with reference to FIGS. 18 to 22.
This rear air conditioning unit 1 has a casing 6, and has an evaporator 7 acting as a heat exchanger for air conditioning, and a blower 8 fan for drawing air from the passenger component (i.e., inner air) to pass through the evaporator 7 and blowing the heat-exchanged air into the passenger component, in the casing 6. Reference number 9 shows an inlet opening and a reference number 10 shows an outlet opening in these figures.
In the above disclosed air conditioning unit 1, the casing 6 is divided into two parts, i.e., upper and lower parts (6a, 6b), and units of cross-flow fans 8A as shown in FIG. 19 or units of sirocco-fans 8B as shown in FIG. 20 are employed as the blower 8.
Furthermore, the above disclosed air conditioning unit 1 is mounted in the ceiling of the passenger component and the evaporator 7 to exhaust drainage is internally installed in the unit. Therefore, in this unit, treatment of this drainage is an important matter.
The conventional treatment of the drainage is explained with reference to FIGS. 21 and 22. FIG. 21(a) shows a plan view of a heat exchanger mounting surface of the lower casing 6b, and FIG. 21(b) shows a front view of the lower casing 6b. Commonly, in this unit, the drainage is led to drain openings 11 which are formed on both sides of the lower casing 6b and exhausted to the outside of the vehicle via drain hoses (not shown) connecting to the drain openings. Therefore, the lower casing 6b has a convex curved shape, with its center at the top and both sides located at the bottom, as sown in FIG. 21(b).
Moreover, in the lower casing 6b, the heat exchanger mounting surface which is located at the front side of the vehicle functions as a drainage pan. Furthermore, this surface and a blower mounting surface which is located at the rear side of the vehicle are molded into one body.
The above disclosed air conditioning unit 1 is operated during movement of the vehicle. Therefore, it is necessary to treat the drainage in anticipation of all situations that may occur while traveling. More concretely, it is necessary to prevent the leakage of the drainage into the passenger component even if the drainage moves back and forth because the vehicle climbing or descending or accelerating and decelerating, or even if the drainage moves left and right because the vehicle turns. In the conventional rear air conditioning unit 1, to cope with the above requirement, four drains 18, 19, 20, 21 which are formed by ribs 12, 13, 14, 15 extending along the width direction and ribs 16, 17 extending along the front and rear directions, are provided as shown in FIGS. 21(a) and 22.
Moreover, reference number 22 in these Figures indicates an insulation member which is installed between the lower casing 6b and the evaporator 7 for heat insulation and for protection of the evaporator 7. Moreover, the rib 12 which is located at the front end forms part of the front surface of the casing 6, and the inlet opening 9 opens to the upper side of the rib 12.
The above mentioned rear air conditioning unit 1 is mounted in the ceiling of the passenger component, and therefore, a reduction of the thickness of the unit for the most miniaturization is required to secure headroom for the passenger. Especially, in a sedan type passenger car having a lower height, which corresponds to a one-box car, there is a strong demand for miniaturization of the unit because the height of the passenger component is low.
However, in the conventional rear air conditioning unit 1, the blower 8 which is installed in the casing 6 has an exclusive casing 8a (refer to FIG. 18). Consequently, the space for the casing 8a becomes one obstacle to the miniaturization of the unit.
Furthermore, it is necessary to raise the height of the rib 12 which is located at the front end and forms a part of the front surface of the casing 6 as much as possible, to prevent spillage of the drainage which moves forward by its inertia when the vehicle slows quickly, for example.
However, as disclosed above, the thickness of the rear air conditioning unit 1 is restricted by the location of the unit. Therefore, the opening area of the inlet opening 9 becomes smaller and ventilation resistance increases as the height of the rib 12 is increased. This increase of the ventilation resistance can lead to an increase in both the noise of the rear air conditioning unit 1 and the power consumed by the blower 8.
This present invention is provided in compliance with the above circumstances, and the purpose of the present invention is provide an overhead type air conditioning unit for a vehicle which can handle the drainage securely and miniaturization of the rear air conditioning unit by reducing the thickness of the unit.